1. Field of the Invention
The present invention relates to a 5×3 wavelet transform apparatus used in JPEG 2000 or the like for example.
This application claims the priority of the Japanese Patent Application No. 2002-052040 filed on Feb. 27, 2002, the entirety of which is incorporated by reference herein.
2. Description of the Related Art
Recently, a still image compression method called JPEG 2000 (ISO/IEC JTC 1/SC 29/WG1) has been proposed. JPEG 2000 adopts a wavelet transform in which the 5×3 filter is lifted. In this method, a conversion for decomposition of original image data into low- and high-frequency components is called “forward transform” and a combination of such low- and high-frequency components into the original image is called “inverse transform”.
Also, JPEG 2000 adopts reversible wavelet transform or irreversible wavelet transform, either of which the user can selectively adopt.
However, in case a JPEG 2000 encoder/decoder is built by making a 5×3 wavelet filter as a hardware or software, it is necessary to form a forward reversible transform module, inverse irreversible transform module and an inverse reversible transform module, which will lead to a larger circuit scale.